People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Drugs for erectile dysfunction are commonly seen as solution pills to a man’s bedroom woes. They aim to eliminate stress some men get from feeling that they have to perform well in-between the sheets, and to keep an erection long enough for sexual excitement and satisfying sex. Tablets for erectile dysfunction, such as Viagra, have been found to improve a man’s sex life, but they don't improve relationship satisfaction, or tackle the emotional and psychological causes of impotency, according to a recent study.

Erectile dysfunction typically occurs when a man can no longer get an erection, or keep an erection for long enough to have sexual intercourse. The Cleveland Clinic says that those who are able to achieve an erection are physically or visually stimulated, as their brain sends out a signal that tells the muscles in their penis to relax. The corpa cavernosa — two tubes that run the length of the penis — become engorged, which causes the penis to expand and harden. The penis remains erect once the two tubes are expanded and effectively block the veins that carry blood away from the penis.

Since the ability to achieve an erection involves the brain, hormones, emotions, nerves, muscles, and blood vessels, a problem with any of these factors will impact a man’s sexual performance. Also, a combination of physical and psychological issues can cause a downward spiral of erectile dysfunction. For example, a physical problem can slow down a man’s sexual response, which in turn can generate anxiety about keeping the erection, therefore leading to further dysfunction.

Researchers investigated the psychosocial outcomes associated with erectile dysfunction before treatment with an erection drug, and the change in these outcomes after use of the drug in men with the condition. A thorough analysis of 40 clinical trials examined whether the phosphodiesterase type 5 (PDE5) inhibitor made a difference in the quality of life in men between 45 and 65 years old.

The compilation of studies included sample sizes of men who had experienced erection problems for at least six months, but did not have any other illness that could have led to their sexual woes. The men, who were given either tablets or placebo pills, were followed for between six to 12 weeks, on average, to determine the effects of the pills.

Those who took the PDE5 inhibitor were reported to have more self-esteem and confidence than before undergoing treatment, and also reported being more satisfied with the sexual aspect of their relationships when compared to the men who took the placebo pills. The researchers found that most of the participants in the clinical trials who had erectile dysfunction also had symptoms of depression. The men who were administered the erection drug were less likely to have symptoms of depression after treatment. Depression, anxiety, or other mental health conditions, along with stress can interfere with sexual feelings and cause or worsen erectile dysfunction, says the Mayo Clinic.

While the PDE5 inhibitor helped men with their sex life, they failed to improve relationship satisfaction and life quality. The systematic review found that the treatments didn’t make any difference in men's overall satisfaction with their relationships. The researchers believe more emphasis needs to be placed on the psychological issues of erectile dysfunction, saying that their study adds to the mounting evidence that the negative effects of erectile dysfunction extend beyond the inability to have sex, according to LiveScience.

Andrew Kramer, a urologist at the University of Maryland Medical Center who wasn't involved in the study, echoed the remarks of the scientists. “It's simplistic to think that fixing an erection issue would solve relationship issues. Happiness is very complicated, and erections are just one small piece of it ... a lot of couples still need additional therapy,” he told LiveScience.

Although the study has delved into a subject that warrants further investigation, the researchers suggest the current study does present some limitations. They noted it is possible that the clinical trials did not find an improvement in men’s overall life and relationship satisfaction because the participants were relatively pleased with their lives at the start of the study. Another possibility is the trials did not follow up long enough to carefully examine the psychological outcomes of the treatment.

In a similar study, researchers found that men who were taking Viagra did not experience a significant amount of change in relationship satisfaction. Viagra did not boost relationship satisfaction or life quality even among couples who displayed room for improvement at the time of the study.

These findings highlight the importance of how sexual problems can affect men’s happiness and relationships. In combination with the use of erection drugs, men may benefit from psychosexual counseling to address the sexual problems caused by their emotions.